Commit 820381d3 authored by Josh Smeaton's avatar Josh Smeaton Committed by Tim Graham
Browse files

Fixed #24486 -- Documented method to provide output_field to mixed F expressions

parent 937643a1

docs/ref/models/expressions.txt

+11 −0
Original line number Diff line number Diff line
@@ -274,6 +274,17 @@ should define the desired ``output_field``. For example, adding an 
``IntegerField()`` and a ``FloatField()`` together should probably have

``output_field=FloatField()`` defined.



.. note::



    When you need to define the ``output_field`` for ``F`` expression

    arithmetic between different types, it's necessary to surround the

    expression in another expression::



        from django.db.models import DateTimeField, ExpressionNode, F



        Race.objects.annotate(finish=ExpressionNode(

            F('start') + F('duration'), output_field=DateTimeField()))



.. versionchanged:: 1.8



    ``output_field`` is a new parameter.